The long-running bidding battle for Sky will be decided in a quick-fire auction finishing on Saturday night, Britain's Takeover Panel has announced.

The Panel said Rupert Murdoch's 21st Century Fox and US media giant Comcast have agreed to settle the takeover tussle with a three-round auction that is due to kick off at 5pm on Friday and end during the evening of September 22.

The process has been triggered as Fox and Comcast have yet to announce their best-and-final bids for pay-TV giant Sky ahead of the September 22 deadline.

The Takeover Panel said the first round of the auction will take place on Saturday, with Fox firing the gun on proceedings, as it currently has the lowest bid.

The winner of the auction will be announced "as soon as practicable" after it finishes on Saturday in a dramatic end to one of the City's most complex and convoluted takeover sagas in recent memory.

If it can win the battle to buy Sky before the Disney deal closes, then Disney will take full ownership of Sky when it closes its own takeover of the Fox assets.

But it has found a determined rival in media and telecoms group Comcast - which owns NBC Universal and is the largest cable operator in the US.

If Comcast takes over Sky, it will become the biggest pay TV provider in the world, with around 52 million customers after adding Sky's 23 million subscribers.

For Comcast and Disney, winning Sky would mark a welcome small victory in the fight against the rise of Netflix and Amazon.

Fox has faced heavy scrutiny from the UK Government and competition watchdogs over its Sky takeover plans, while Comcast's bid was cleared by regulators early on in the process.

Fox was finally given the Government's all-clear to take over Sky in July, although it has had to pledge to offload Sky News to Walt Disney, and provide a Disney-owned Sky News channel with funding of at least £100 million a year for 15 years.